When patients are examined in an imaging system having a gantry, such as a computed tomography system, a magnetic resonance tomography system or a PET system, the patient has to be supported in the gantry. To this end the patient is positioned on a patient support plate, which can be moved into the gantry. The spatial extension of the gantry—typically in the form of a hollow cylinder with an external diameter of approx. 2 m—means that the patient support plate has to be at a distance of between 70 and 90 cm from the ground to be moved into the gantry. For the patient to be able to climb easily onto the patient support plate beforehand however, a distance of 55 cm from the ground should not be exceeded. Vertically adjustable patient support apparatuses are therefore now widely used with imaging systems with larger gantries.
An optimum workflow, in particular when immobile patients are supported, can be achieved when the patient support apparatus can be undocked, i.e. released, from the medical device and can also be operated in a mobile manner. This option is particularly important when the medical device is an imaging system operated according to the magnetic resonance principle, for example magnetic resonance tomography system or a magnetic resonance PET system. The extremely strong magnetic field active in the examination region means that the patient cannot be moved directly into the examination space using the normal patient support apparatuses used for hospital transportation (e.g. patient couch, trolley, hospital bed, etc.). With a patient support apparatus that can be docked and undocked, i.e. a patient support apparatus that can be connected in a releasable manner to the medical device, the patient can be safely transferred for example from a hospital bed to the patient support apparatus that can be connected to the medical device in a magnetic field-free space (preparation space). To this end the mobile undockable patient support for connection to a magnetic resonance tomography system must be designed to be sufficiently non-magnetic so that it is not attracted by the magnet in its leakage field. It is also advantageous if the mobile patient support apparatus can also be adjusted vertically in the undocked state, in particular being able to be adjusted to the level of a hospital bed, to facilitate the transfer of an immobile patient. A low overall weight of the patient support apparatus is also an important prerequisite for mobile deployment.
Numerous patient support apparatuses with vertically adjustable patient support plates are known in medical engineering. They are generally fitted with electric or hydraulic lifting systems. Electric lifting systems are generally moved by a spindle drive with an electric motor. They can generally only be adjusted by means of this motor and have to be accompanied by an energy storage unit (battery or accumulator) when deployed in a mobile manner. Hydraulic lifting systems are generally moved by a lifting piston, into which pressurized hydraulic oil is fed. They provide an efficient means of manual adjustment by means of foot pedals in conjunction with a piston pump.
A patient support apparatus is known from patent publication DE 42 24 695 C1, in which a hydraulic pump is driven by an electric motor.
A mobile patient support apparatus is known from publication EP 0 209 326 A2, in which manual vertical adjustment by means of foot pedals in conjunction with a piston pump is possible in the undocked state. A further hydraulic pump is present for automatic vertical adjustment in the docked state, this pump being driven by way of a hydraulic motor disposed outside the patient support apparatus.